FIU researcher Mauricio Rodriguez-Lanetty said dives from the surface would be too short and risky to accomplish much in the nursery. But divers living in the pressurized lab for days or weeks at a time can work longer in deeper waters.

Astronauts planted the endangered corals on tree-like structures made from plastic pipes in 2015. They’ve continued working in the nursery during NASA training missions over the last two years.